Wafer thinning apparatus having feedback control and method of using

A method of thinning a wafer, the method comprising:

• measuring an initial thickness of a wafer;
• determining a polishing time based on the initial thickness;
• polishing the wafer for a first duration equal to the polishing time to reduce the initial thickness to a polished thickness;
• measuring the polished thickness;
• updating a material removal rate of the polishing process based on the measured polished thickness, wherein updating the material removal rate comprises updating a lookup table;
• and
• etching the polished wafer for a second duration equal to an etching time to obtain an etched wafer, wherein the wafer has a total thickness variation of less than or equal to 0.15 μm after etching the polished wafer.

A method of thinning a plurality of wafers, the method comprising:

• measuring an initial thickness of each wafer of the plurality of wafers;
• determining a first polishing time for a first set of wafers of the plurality of wafers based on the measured thickness for the first set of wafers of the plurality of wafers;
• polishing the first set of wafers of the plurality of wafers for a duration equal to the first polishing time;
• measuring a thickness of at least one of the first set of wafers of the plurality of wafers to determine a polished thickness of the at least one wafer of the first set of wafers of the plurality of wafers;
• updating a material removal rate of the polishing process based on the measured polished thickness;
• determining a second polishing time for a second set of wafers of the plurality of wafers based on the measured thickness for the second set of wafers of the plurality of wafers and based on the updated material removal rate;
• and
• calculating an etching time for each wafer of the plurality of wafers using the polished thickness of the at least one wafer.